Ammunition feed



June 12, 1945. A. CORTE 2,378,191

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Patented June 12, 1945 AMMUNITION FEED Alfred Corte, Glendale, Calif.,assignor, by mesne assignments, to Lockheed Aircraft Corporation, acorporation of California Application December 27, 1941, Serial No.424,636

'1 Claims. (01. 89-33) This invention relates to an improved ammunitionfeed especially adapted for use with machine guns and the like whichmust be freely movable about one or more axes, as when mounted inairplane, boat or tank turrets, providing both traversing and elevatingmovements for the gun or guns carried therein.

The ammunition supply for the machine guns of a movable turret isordinarily made integral with the gun mount; in which case the feedingis little dilferent from that of a stationary gun, or, it is placed onsome more or less stationary part of the turret. With the latter type ofinstallation, itis usual to provide a long loop of ammunition betweenthe supply box and the gun to compensate for the varying distancebetween the gun and the box as the gun is moved in traverse. Inaddition, the cartridge belt must be twisted through some 110 to allowthe belt to follow the angular movement of the gun as it is elevated andlowered.

The integral mounting arrangement is, of course, the simplest and themost reliable. However, it means placing the ammunition box close to thegun and hence taking up space inside the turret. If the ammunitionsupplyrequirements exceed a certain number of cartridges, the size of thenecessary supply box rather than the size of the gunner will determinethe size of the turret.

Rather than increase the size of the turret, the practice has been tomove the ammunition supply box to the lower part of the turret and touse the twisted loop. This again is subject to the criticism that undercertain conditions'of acceleration, and unless the ammunition belt hasbeen loaded just right, the shells will not enter the gun properly andthe gun will jam.

Another consequence of moving. the ammunition supply down into'thefuselage of the plane is v the need for a separate device to assist inthe lifting of the belt up to the gun, since the gun is limited intheweight of belt which it can lift and still operate reliably, .Themost successful of these prior devices has been an arrangement in whichthere is provided a small reservoir of cartridges near the gun and withthe main supply below. The cartridge belt runs from the main supply boxup to the reservoir, which may consist of one or several loops locatednear the gun. The lift from the main supply box is accomplished by anelectric motor drive which is connected to a limit switch in such amanner that it will maintain the number of cartridges in the reservoirwithin certain limits. The gun itself will draw the cartridges from thereservoir. Although simple in principle, the extra equipment needed forthis device. is sufficiently complicated that occasional failures may beexpected, particularly under the diversity of conditions such asextremes of acceleration and temperature which are encountered inservice. I

It is accordingly an object of this invention to develop an ammunitionfeed which operates directly from the gun and hence is at least asreliable as the gun and requires no separate power system. In principle,each time the gun fires a round, the power feed advances onecartridge.The power available is sufficient to lift the ammunition under the mostsevere conditions of ad verse acceleration. Yet, since the feed isintermittently: operated by the gun, one and only one cartridge will be,advanced for each cartridge fired even for accelerations considerablyless than one g.

Other and further important objects of this invention will be apparentfrom the disclosures in the specification and the accompanying drawings.

This invention in its preferred form is illustrated in the drawings andhereinafter more fully described,

A preferred form of this invention is shown diagrammatically in thedrawings, wherein:

FigureI is a central vertical section through a twin gun airplane turretshowing the cartridge feeding chutes and mechanism for elevating thecartridges from an ammunition container to the gun breech, the dottedlines showing the position of the upper chute when the gun has beenelevated for vertical fire.

Figure II is a half of a vertical cross-section of the turret with onegun and its feed mechanism shown in elevation from the muzzle end of thegun.

Figure III is a top plan view of Figure II with the turret shellomitted.

Figure IV is a fragmentary detail in plan view, partly in section toshow the spent gas operating mechanism associated with the gun barrel.

Figure V is an elevation view of the spent gas 7 operating mechanism ofFigure IV, with the gun barrel omitted.

Figure V1 is a muzzle end view of Fig. IV. Figure VII is an enlargeddetail view of the cartridge chutes and cartridge feeding mechanism.

Figure VIII is a further enlarged detail of the-upper or final cartridgefeeding mechanism whicl'iideliversthe cartridges through a right angleturn, in the plane of the belt, to the conventional gun feedingmechanism.

As shown on the drawings I have chosen to illustrate the powerammunition feed in connection with an airplane turret A such as has beendisclosed in my previous application, Serial No. 362,067, filed October21, 1940. However, I have simplified the turret enclosure by theommission of that part thereof which rotates in elevation about ahorizontal axis. For present purposes it will be convenient to considerthe gun B as elevating about the axis C, the gun mounting and elevatingmechanism being omitted. As shown and described in my above mentionedcopending application, a turret shell ll] rotates about its verticalaxis in a horizontal ring bearing 'll forming part of an airplanestructure, a central pedestal l2 and column l3 being connected theretoat the axis C of the elevating portions of the turret.

The gun B, one of a pair disposed on either side of the gunner, ismounted on, and moves as a unit with the elevating portions of theturret. The pedestal I2 and column l3 preferably do not carry the weightof the turret, which weight is supported by the ring bearing H, butserve as a power and communications conduit, and support the ammunitionfeed chutes of this invention. I

It is not feasible to carry an adequate supply of ammunition in acontainer attached to and elevating with the gun, so I provide agenerally arcuate container l4 suspended by brackets l5 below andapproximately aligned with the ring gear H, in order to provideclearance within the turret for the gunners seat and foot rest, as wellas entrance to such space. Accordingly, the container It rotates withthe turret as the latter is traversed in azimuth. Because of the arcuateshape of the container its capacity is increased if the cartridges areplaced therein point inwards. Thus the cartridges l6, linked together bya belt or disintegrating links, are drawn out of the container at onecorner I! and are twisted through an angle of approximately 135 whilehanging in a loop l8, prior to entering a lower chute l9 wherein thecartridges point away from the longitudinal center line of the turret.

From the lower chute [9 the cartridges hang in a second loop prior toentering an upper chute 2| which is attached to and elevates with thegun B. As the cartridges leave the upper chute they feed around a curvedchute 22 into a position parallel to and adjacent the gun breech butslightly therebelow, the regular gun feeding mechanism being relied uponto lift the few cartridges suspended between the gun breech and thesurface of the curved chute 22. The second hanging loop 20 providessufficient slack'in the cartridge feed belt to provide for the elevatingmotion of the gun, since the gun and the upper chute 2i pivot about theturret axis C and the chute therefore takes up the slack of the loop 26when moved to the dotted line position of Figure I.

The power for the ammunition feed is derived from the residual pressureof the gas in the gun barrel just after the bullet has left the muzzle23 as shown in detail in Figures IV and V.

This gas is allowed to escape from the muzzle into an expansion chamber24 which has a tube 25 slightly larger than the bore of the gun for thebullet to pass through, and through which the gases eventually escape.The purpose of this expansion chamber 24 is two-fold. First, it createsa back pressure on the gases for a short time so the combustion cancontinue. Although this continued combustion time adds nothing to thevelocity of the bullet, it does allow at least part of the burning ofthe gases to be completed within the chamber, so that when the gasesfinally emerge from the gun, a large fraction has ceased glowing andhence the flash is considerably reduced. Also, the after-burning tendsto prolong the pressure interval and thus provide continued power behindthe piston. Secondly, by means of this expansion chamber, at least apart of the energy represented by the residual pressure is madeavailable to operate the ammunition feed. A cylinder 26 and piston 27are located adjacent to the expansion chamber with an opening 28 leadingfrom the expansion chamber into the cylinder. At the end of the pistonstroke, the cylinder chamber is vented to the atmosphere by means ofports 29 in the cylinder wall located so that during the stroke, theyare closed on. by the piston but at the end of the stroke, the head ofthe piston has moved past the ports so that the gas is allowed to escapefrom the cylinder.

Immediately after the bullet has left the gun muzzle, the gases in thegun barrel escape from the muzzle into the expansion chamber 24, and.

the pressure in the chamber rapidly builds up. The gases escape partlyinto the head space of the cylinder and partly directly to theatmosphere through the exit port. In a short time, the gases in thechamber will have escaped through the exit port and the pressurewillhave dropped to atmospheric. The gas in the cylinder can expand in twoways: first, by moving the piston and second, back through theconnecting port to the chamber and thence to the atmosphere. During thefirst part of the cycle, the pressure in the expansion chamber is highand the gas in the cylinder has no alternative but to move the piston.Later in the cycle, the movement of the piston is dependent upon therelationship between the size of the piston and the size of the portleading into the expansion chamber. In any case. the high initial forceof the piston serves to start th load moving and the remaining pressurekeeps it moving, until by the end of the piston stroke, the load hasbeen allowed to gradually come to a stop.

The piston 21 is connected by means of a wrist pin 30 and outsideconnecting rods 3| to a spring shock absorber 32 and thence to acoupling 33 to two cable drives 34 and 35 which transmit the pistonmovement in tension to shell advancing ratchet mechanisms, on of whichis shown in detail in Figure VIII. One cable 35 is led into a coupling36 which divides into two cables 31 and as each leading to a similarratchet mechanism. The three ratchet mechanisms are located respectivelyinside the ammunition container M, at the bottom of the lower chute l9,and at the turn of the upper chute 2|. Since the three ratchetmechanisms are identical, it will be convenient to describe the lastmentioned, which is detailed in Figure VIII.

Each of these shell advancing devices consists of a sprocket, wheel 39over which the cartridges and links travel in much the same manner as achain over a sprocket. The sprocket wheel is turned through one tooth,by a lever arm 40 which drive the sprocket through a pawl 4! and ratchet42 arrangement which in turn is actuated by the flexible cable 34 fromthe piston 21. As soon as the cartridge has'been advanced, an escapementmechanism bears directly upon'the cartridge in such a manner as to keepthe belt from falling back, while the piston and the lever arm return tothe rest position.

The escapement mechanism is conveniently associated with one or more ofthe ratchet mechanisms; and comprises a detent device working inconjunction with the ratchet mechanism to prevent the cartridges fromfalling back after they have been lifted by the ratchet, and also toresist the inertia of the moving Cartridges fro carrying them past morethan one tooth of the ratchet. The position of the escapement in FigureVIII may be considered the rest position, wherein a lever 44 is pivotedat 45 to a bracket on the chute and has a roller 45 bearing on onecartridge while a second lever 41 is pivoted to the second roller 49clear of the approaching cartridge shown as substantially level with thesprocket.

When the first roller 46 ridesup on the next car tridge the secondroller 49 drops down behind the following cartridge until the positionof rest is again reached.

A previously mentioned, the total lift from the f ammunition containerto the-gun is accomplished in four stages. First, the ammunition isbrought to the mouth of the container. Second, it goes through a loopand enters the lower portion of the chute, which lower portion isstationar with respect to the traverse ring and the ammunition box.Third, the belt goes through-a second loop and enters the middle chute,which middle chute is stationary with respect to the guns and hencemovable in elevation with respect to the lower chute. Fourthly, it goesthrough the upper chute where the belt makes a right angle turn in theplane of the belt to enter the guns with the nose of the cartridgepointing forward.

The first stage of the lift is accomplished by one of the ratchet motorsplaced in the mouth or exit of the ammunition container. It lifts thecartridge belt to the top of the container where the exit is located.The second ratchet motor is located at'the bottom of the lower chutewhere it lifts the belt from the first loop and, pushes it through thechute to the second loop. The third motor is located between themiddleand upper chutes, where it serves to draw the belt from the second loopinto and through the middle chute and feeds it into the upper chute.Here, the

regular gun feeding mechanism takes over to accomplish the fourth stageof the processof lifting the cartridges from the ammunition container tothe gun.

The second phase of the ammunition feed problem is the accomplishment ofthe lifting of the cartridges without interfering with the operation ofthe turret. As mentioned previously, it is not feasible to allow theentire ammunition container to move with the guns so that some provisionmust be made for the movements of the turret in traverse and inelevation.

Since the ammunition containers are attached to the traverse ring, thecontainers move with the (ill - ward.

turret in traverse. The cartridge belt is led-up to the gun so that itdoes not interfere with or is not interfered with by the movement of theguns in elevation. This is accomplished by leading the belt to a pointnear the axis'of rotation of the turret in elevation. This is done insuch a manner that the apex of the dihedral angle formed by theintersection of the planes of the cartridge belt as it approaches and asit leaves the center of the turret is on or near the axis of rotation ofthe turret in elevation. Thus, the effect on the cartridge belt ofelevating the turret is merely to cause the belt to fold about whicheverof the shells is at the apex. This is a perfectly normal movement of thebelt and is accomplished without difiiculty. In practice, the foldingdoes not take place exactly at the axis, but about six inches therefromand a small loop is provided for compensation. After executing thisfold, the cartridges are able to move with the gun but have theirlongitudinal axes perpendicular to the axis of the gun, while to beuseful, the axes must be parallel to that of the gun with the noses for-It is necessary to turn the belt through a right angle lying in theplane of the belt. In order to have the shells come out 'of this turn inalignment with the gun breech the belt is led forward and then reversedin direction, with the noses of the shells on the inside of the arc anda very compact arc will be realized.

It will be noticed that the belt is made to flex in its normal mannerand even these fiexures I take place with the assistance of guidingchutes and sprockets, so that there is no chance of the belt binding orentering the gun in other than the normal manner. It would also benoticed that although the ammunition feed derives its power from thegun. it does not in any way affect the operation of the gun, since thesource of power is the gas remaining in the barrel after the bullet hasleft the gun.

Having thusdescribed my invention and the present preferred embodimentsthereof, I desire to emphasize the fact that many modifications may beresorted to ma manner limited only by a just'interpretation of thefollowing laim.

I claim as my invention:

1. Mechanism for advancing a cartridge belt to a gun comprising a gunmount for movement in traverse and elevation, a container curvedsubstantially about the axis of traverse movement of the gun andconstructed and arranged to move with the gun intraverse, the belt beingcontained in the container so that its cartridges are in substantiallyradial relation to said axis.the container having an outlet for thebelt, a first chute fixed relative to the container and extending fromadjacent said outlet in the general direction of the gun. the firstchute being adapted to contain and direct the belt so that itscartridges are sub stantially tangent to circles concentric with saidaxis. belt advancing means on the container and first chute operable tomaintain a slack twisted loop in the belt between said outlet the firstchute wherein the cartridges are twisted into positions at right anglesto the plane of elevation of the gun, a second chute constructed andarranged to move in traverse and elevation with the gun and adapted todirect the beltinto the gun, the second chute having its belt receivingend spaced from and related to the belt discharging end of the firstchute to allow a slack loop of the belt to hang between the chutesadjacent the axis of elevation movement of the gun, belt advancing meanson the second chute for advancing the belt and for maintaining thesecond named loop, and means forioperating the first and second namedbelt advancing means in unison.

2. A mechanism for transporting linked cartridges from a container to aposition adjacent a gun, the mechanism comprising spaced chutes adaptedto guide the linked cartridges from the container to a position adjacentthe gun, supporting means for each chute, one of said supporting meansbeing movable with respect to the other supporting means, sprocket meanson each chute adapted to engage the linked cartridges therein andadapted to advance the same, means on the chutes for engaging the linkedcartridges to maintain a slack loop in the linked cartridges extendingbetween the spaced chutes, and means for intermittently moving thelinked cartridges including power transmitting means interconnecting thesprocket means, and power means operatively connected with said powertransmitting means.

3. A mechanism for transporting linked cartridges from a container to aposition adjacent a gun, the mechanism comprising spaced chutes adaptedto guide the linked cartridges from the container to a position adjacentthe gun, supporting means for each chute, one of said supporting meansbeing movable with respect to the other supporting means, sprocket meanson each chute adapted to engage the linked cartridges therein andadapted to advance the same, means on the chutes for engaging the linkedcartridges to maintain a slack loop in the linked cartridges extendingbetween the spaced chutes, and means for intermittently moving thelinked cartridges including a cylinder and piston mechanism adapted tobe operated by the muzzle blast of said gun, and means operativelyconnecting said cylinder and piston mechanism with said sprocket meanson the chutes so that said cylinder and piston mechanism simultaneouslyoperates said sprocket means.

4. A mechanism for transporting linked cartridges from a container to aposition adjacent a gun, the mechanism comprising spaced chutes adaptedto guide the linked cartridges from the container to a position adjacentthe gun, supporting means for each chute, one of said supporting meansbeing movable with respect to the other supporting means, sprocket meanson each chute adapted to engage the linked cartridges therein andadapted to advance the same, means on the chutes for engaging the linkedcartridges to maintain a slack loop in the linked cartridges extendingbetween the spaced chutes, and means for intermittently moving thelinked cartridges including a cylinder and piston mechanism adapted tobe operated by the muzzle blast of said gun, means operativelyconnecting the sprocket means of said chutes, and a resilient impulsetransmitting connection between said cylinder and piston mechanism andthe last named means whereby said cylinder and piston means is operableto simultaneously operate said sprocket means.

5. A mechanism for transporting linked cartridges from a container to aposition adjacent a gun, the mechanism comprising spaced chutes adaptedto guide the linked cartridges from the container to a position adjacentthe gun, supporting means for each chute, one of said supporting meansbeing movable with respect to the other supporting means, sprocket meanson each chute adapted to engage the linked cartridges therein andadapted to advance the same, means on the chutes for engaging the linkedcartridges to maintain a slack loop in the linked cartridges extendingbetween the spaced chutes, and means for intermittently moving thelinked cartridges including a ratchet means at each sprocket means foroperating the same, a cylinder and piston means adapted to be operatedby the muzzle blast of said gun, and means operatively connecting saidratchet means with the cylinder and piston means to be operated thereby.

6. A mechanism for transporting linked cartridges from a container to aposition adjacent a gun, the mechanism comprising spaced chutes adaptedto guide the linked cartridges from the container to a position adjacentthe gun, supporting means for each chute, one of said supporting meansbeing movable with respect to the other supporting means, sprocket meanson each chute adapted to engage the linked cartridges therein, ratchetmeans at the sprocket means operable to intermittently advance the ame,a power operated mechanism connected with the ratchet means operable forproducing simultaneous advancement of the sprockets, and escapementmeans at the sprocket means for resisting over travel of the linkedcartridges and operable to maintain a slack loop in the linkedcartridges extending between the spaced chutes.

7. An ammunition advancing mechanism for transporting linked cartridgesfrom a container to a position adjacent a gun movable in elevationrelative to said container, said mechanism comprising a first chuteadapted to extend from the container and operable to guide the linkedcartridges therefrom, means for supporting the first chute to bestationary with respect to the container, a second chute, means forsupporting the second chute to adapt it for movement in elevation withthe gun, the linked cartridges being adapted to extend from the firstchute to the second chute, a cartridge advancing means on each chute,members on the chutes for engaging the cartridges to provide a slackloop in the linked cartridges which extend between the chutes to allowfree flexing of the linked cartridges during the movement of the secondchute relative to the first chute, and guide means stationary withrespect to the second chute adapted to turn the linked cartridges to agiven position with respect to the gun after delivery from the secondchute.

ALFRED CORTE.

